Project Summary Approximately 14,500,000 Americans meet diagnostic criteria for current alcohol use disorder (AUD), and the deaths of 88,000 Americans are attributed to alcohol misuse annually. There is an urgent need to bring our current scientific understanding of the neurobiology of AUD to bear on the challenges of developing novel treatments and biomarkers of relapse risk for individuals with AUD. The purpose of this new 2-year exploratory R21 research project is to examine the role of circulating endogenous cannabinoids (eCBs) in predicting alcohol relapse risk and resiliency, using archival, de-identified, longitudinal clinical research data and associated plasma specimens frozen and maintained at -80 degrees. Clinical and eCB data were collected from 300 individuals (69% male, mean age 40.3 yrs) with AUD who completed human laboratory studies assessing reactivity to affective priming and in vivo alcohol cue exposure. The eCB signaling system is a neuromodulatory system known to buffer stress-like responses. Pre-clinical evidence suggests that repeated excessive alcohol consumption is associated with the blunting of the on demand release of eCBs which provide an important source of inhibitory influence in brain stress signaling and mood homeostasis. Deficient eCB tone as a result of chronic alcohol misuse may thus reflect the critical loss of signaling elements that contribute to alcohol-related motivational pathologies, i.e., negative affect, craving, insomnia and relapse. Circulating levels of eCBs have been found to be lower in humans with major depression, posttraumatic stress disorder and following exposure to chronic stress. Unknown, however, is what role the eCB system plays in stress-related relapse associated with alcohol use disorder. The purpose of this proposal is to test the hypothesis that circulating eCB levels will identify individuals having heightened relapse risk or resiliency as reflected in responsivity to affective priming and in vivo alcohol cue exposure in a human laboratory model of craving and relapse risk in AUD. To test this hypothesis, Specific Aim 1 is designed to determine if eCB levels (AEA, 2AG, PEA, OEA) in AUD subjects obtained at the time of cue testing vary in relation to reactivity to alcohol cues, with high reactivity representing a heightened risk for relapse, and low reactivity representing resiliency to relapse risk, and Specific Aim 2 is designed to determine if baseline eCB concentrations predict subsequent eCB levels. The present proposal will provide key information linking craving driven by negative emotional states to circulating eCBs. Significant association could provide a marker for vulnerability for craving and/or resilience to craving either of which could provide a framework for a future clinical trial outlining key markers for recovery and/or a clinical trial of medications to treat AUD by engaging the eCB system.